Mobile SEO
Mobile-Friendly Test
Fast static checks on the HTML, plus real Lighthouse scores and Core Web Vitals field data from Google PageSpeed Insights.
- Fetched live by our server
- Nothing stored
The tool
Enter a public URL to run the static checks, then run Lighthouse if you want lab scores and field data.
Loading the tool…
The URL you enter is sent to our server, which requests that page from the public internet and returns the response to your browser for analysis. We do not store the URL or the response, and we do not add either to analytics. Requests come from our server, not from your device or from the crawlers being simulated, so a site that blocks data-centre addresses or verifies crawlers by IP may answer differently.
What this tool checks
- Viewport meta tag: width=device-width, initial-scale and whether zoom is blocked
- Inline styles wider than a phone screen and fixed-width tables, iframes and images
- Inline font sizes below 12 pixels
- Images without width and height, which cause layout shift, and images without srcset
- Plugin content such as object and embed elements that phones cannot run
- Home-screen icon and theme colour
- With PageSpeed Insights: Lighthouse performance, accessibility, best practices and SEO scores, failing audits, and Core Web Vitals field data where Google has enough real-user data
How to read the results
- Read the static checks first. A missing or fixed-width viewport is the single most common reason a page is not usable on a phone.
- Treat High and Medium findings as things to fix, and Info items as things to confirm.
- Run Lighthouse for lab scores. Lab results vary from run to run, so compare several runs rather than reacting to a single number.
- Field data shows what real Chrome users experienced over the last 28 days. When it is available, it matters more than the lab score.
About this tool
What happened to Google’s Mobile-Friendly Test
Google retired its Mobile-Friendly Test, the Mobile Usability report in Search Console and the Mobile-Friendly Test API in December 2023. Lighthouse, which also powers PageSpeed Insights, still audits many of the same issues alongside performance and accessibility, so this tool uses it rather than imitating the retired test or claiming to be it.
Two kinds of result, kept apart
Static checks run on the HTML our server fetched with the Googlebot Smartphone user agent. They are instant and cover the problems you can see in markup: the viewport, inline widths and font sizes, image attributes and plugin content. They cannot see what external CSS does, so treat them as a fast first pass.
Lighthouse via PageSpeed Insights loads the page in a real browser on Google’s infrastructure, emulating a mid-range phone on a throttled connection. It returns scores for performance, accessibility, best practices and SEO, the audits that did not pass, and, where available, Core Web Vitals field data from the Chrome UX Report.
The viewport tag
Almost every mobile-friendly page starts with:
<meta name="viewport" content="width=device-width, initial-scale=1">Without it, phones lay the page out about 980 pixels wide and shrink it. Avoid user-scalable=no and low maximum-scale values: they stop people zooming, which fails WCAG success criterion 1.4.4 for resizing text.
Core Web Vitals thresholds
Google assesses Core Web Vitals at the 75th percentile of real page loads:
- Largest Contentful Paint: good at 2.5 seconds or less, poor above 4 seconds.
- Interaction to Next Paint: good at 200 milliseconds or less, poor above 500 milliseconds.
- Cumulative Layout Shift: good at 0.1 or less, poor above 0.25.
The tool also shows First Contentful Paint and Time to First Byte, which help explain a slow LCP. When the page itself has too little traffic, PageSpeed Insights may return data for the whole origin, and the tool says which you are seeing.
Fixing the most common findings
Content wider than the screen
Replace fixed pixel widths with max-width: 100%, flexible grids and media queries. Wrap wide tables in a container with horizontal scrolling rather than letting them stretch the page.
Layout shift from images
Give every image width and height attributes, or a CSS aspect-ratio, so the browser reserves space before the file arrives. Add srcset and sizes so phones download smaller files.
Text too small
Use a base size of at least 16 pixels for body text and avoid inline sizes below 12 pixels.
Plugin content
Phones do not run browser plugins. Replace object and embed elements with native HTML5 video, audio or images, and use responsive iframe wrappers for embedded players.
Checking on a real phone
No automated test replaces a few minutes on an actual phone. Load the page on a small Android device and an iPhone, rotate them, zoom in on body text, tap the menu and every main button, and fill in a form. Problems with tap targets, sticky banners and pop-ups usually show up immediately.
Limits and honest caveats
- This is not Google's Mobile-Friendly Test. Google retired that tool and its API in December 2023.
- The static checks read the HTML and inline styles only. Layout created by external stylesheets or JavaScript, tap target spacing and intrusive interstitials can only be judged in a real browser.
- Lighthouse results come from Google PageSpeed Insights and are labelled as such. Lab scores vary between runs and network conditions.
- Field data only exists for pages and origins with enough Chrome user traffic. Many pages have none.
- Without an API key configured, PageSpeed Insights requests share a small public quota and can fail at busy times.
Google PageSpeed Insights API — When you run Lighthouse, our server sends the URL to Google, which loads the page and returns scores and audits. No personal data is sent. Free, with a per-day quota for the site owner key.
What people use it for
- Checking a page after Google retired its Mobile-Friendly Test
- Finding viewport settings that block zoom for people with low vision
- Getting Lighthouse scores and Core Web Vitals for a page in one place
- Spotting images that cause layout shift on phones
- Giving a developer a clear list of mobile fixes with evidence
Documentation and references
Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
No. Google retired that test and its API in December 2023. This tool combines static checks with Lighthouse results from the official PageSpeed Insights API.
Lab tests are affected by server response time, network conditions and third-party scripts on each run. Compare several runs, and give field data more weight when it exists.
Field data comes from real Chrome users who opted in to sharing usage statistics. Pages and sites without enough of that traffic have none.
Only inline styles and HTML attributes. Stylesheets and JavaScript can change layout, so confirm findings with Lighthouse or a real phone.
Google uses page experience signals, including Core Web Vitals, as part of ranking, but relevance matters far more. A usable mobile page mainly matters because people leave pages they cannot use.
Documentation last reviewed: by the Best Web Developer engineering team.
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